Alfa not working

I’m trying to use the alfa test to draw
a polygon with a hole in it. The hole has
an alfa value of 0 and the rest of the texture has 255. I use the GEQUAL function with a value of 128 but nothing happens…

What is the problem? Is there a special way I have to init my framebuffer to get alfa tests to work? or is it something else?


Called glEnable(GL_ALPHA_TEST)?

And if you are using glAlphaTest() you must pass the alpha reference as a float in the range [0,1].

Well the problem is that I’m enabling alfa test but nothing happens(I use 0.0 -> 1.0 values also). I can’t explain it. My video
card is based on nVidia’s TNT2 and supports
it for sure. The problem is somewhere else

I’m not sure if this will affect the alpha test at all, but it can be that you have to use a framebuffer that support alpha - RGBA. Maybe you are using a RGB framebuffer.